Attaching arrangement for hand-held motor-driven tools

ABSTRACT

The invention relates to an arrangement for attaching a bar of a hand-held motor driven tool to a body of the tool, the arrangement including: at least one bolt, having a first part, securely arranged to the body, and a second part extending from the body, the second part having an engagement portion for engaging a nut; a cover portion adapted to bear against a bar such that the bar is arranged between the cover portion and the body; and at least one nut, captively attached to the cover portion. The nut is adapted to engage the engagement portion of the bolt for securing a bar between the cover portion and the body, the nut having a rotation axis. Thereby, an attachment arrangement is achieved that facilitates changing of bars when the nut used in the attachment arrangement is captively arranged to the cover portion.

TECHNICAL FIELD

The present invention deals with attaching arrangements for hand-heldmotor-driven tools, such as chain saws. Especially, the invention dealswith arrangements for attaching a bar of such a hand-held motor-driventool to a body of the tool.

BACKGROUND

A conventional chain saw includes a body and a guide bar that supportsthe saw chain. A cover clamps the guide bar to the body by means of atightening arrangement, comprising a bar bolt and a nut. For somereasons, e.g. for changing bars or if the chain has come off, the covermay have to be detached from the body. Before the cover can be detached,the tightening arrangement has to be loosened such that the nut isdetached from the bar bolt.

A problem with conventional tightening arrangements, where the nut isloose when detached from the bar bolt, is that an operator of the toolmight lose the nut when detaching the cover from the body, especially ifsituated in a forest. The operator often puts the nut on the groundafter detaching it from the bar bolt, and since the ground is usuallycovered by brushwood and scrub, finding the nut again might bedifficult.

An arrangement where the nut is disposed in the interior of the cover,and consequently can't be lost when detaching the cover, is disclosed inUS2001/0042311. A disadvantage with this arrangement is that the covercan not be pressed towards the body in order to hold the guide bar inposition before starting to thread the nut and the bolt, since the nutwill bear against the bolt before the cover bears against the guide bar.Instead the operator has to hold the guide bar in position with one handwhile threading the nut with the other hand, which makes the attachingoperation complicated.

For large chain saws, having long guide bars, the guide bar tighteningarrangement is exposed to greater strain and two bar bolts withcorresponding nuts are generally used in order to strengthen themounting. An arrangement having two bar bolts is disclosed in U.S. Pat.No. 5,497,557. In a chain saw having more than one bar bolt, thearrangement described in US2001/0042311 is not convenient since it wouldnot allow loosening the nuts one at a time. Instead the operator has tounthread the nuts alternately, which makes the detaching of the coverfrom the body a bit tedious.

There are also other reasons for the operator to detach the cover, notonly for the purpose of changing bar or changing chain. For instance,the operator is doing a weekly overhaul that might include inspection ofbreak components and inspection of the centrifugal clutch. The coverneeds to be detached during such inspections. A further reason fordetaching the cover is for getting access to and cleaning the grove orhole in the bar which provides the chain with chain oil. The groove orhole might become clogged by dirt during long term use in severeoperating conditions and is sometimes in need of cleaning.

SUMMARY

It is an object of the present invention to provide an improved solutionthat alleviates at least some of the mentioned drawbacks with presentarrangements.

The object is achieved by an arrangement for attaching a bar of ahand-held motor driven tool, such as a chain saw, to a body of the tool,according to claim 1 of the present invention. The arrangementcomprises: at least one first engagement means, having a first part,securely arranged to the body, and a second part extending from thebody, the second part having an engagement portion for engaging a secondengagement means; a cover portion adapted to bear against a bar suchthat the bar is arranged between the cover portion and the body; atleast one second engagement means, captively attached to the coverportion, wherein the second engagement means is adapted to engage theengagement portion of the first engagement means for securing a barbetween the cover portion and the body, the second engagement meanshaving a rotation axis. The second engagement means is arranged to movea first distance (A) along the engagement portion of the firstengagement means, in a direction of the rotation axis of the secondengagement means, for securing a bar between the cover portion and thebody. When the first and second engagement means are not engaged, thesecond engagement means is captively attached to the cover portion insuch a way that it is movable a second distance (B) relative the coverportion in a direction of the rotation axis of the second engagementmeans, wherein the second distance (B) is larger than the first distance(A).

Preferably, when the first and second engagement means are not engagedand the cover portion is dismounted from the body, the second engagementmeans is captively attached to the cover portion in such a way that itis movable a second distance (B) relative the cover portion in adirection of the rotation axis of the second engagement means, whereinthe second distance (B) is larger than the first distance (A).

By captively attaching the second engagement means to the cover portionin such a way, it is possible for an operator to put the cover portiononto the first engagement means such that the cover portion can bepressed towards the bar for clamping the bar between the cover portionand the body of the tool before the operator starts to engage the secondengagement means to the first engagement means. Thereby, mounting thecover portion to the bar is facilitated when a second engagement meanscaptively attached to the cover portion is used. The solution alsoensures correct mounting of the cover portion to the body, which isespecially crucial if a brake is mounted in the cover portion.

According to an embodiment of the invention, the cover portion has aninner surface that, when the cover portion is arranged to the body, isdirected towards the body, and an outer surface that, when the coverportion is arranged to the body, is directed away from the body. Thecover portion further has a through aperture extending between the innerand outer surfaces for receiving the second part of the first engagementmeans. The cover portion further comprises at least one recess in whichan attaching portion of the second engagement means is arranged forcaptively attaching the second engagement means to the cover portion.

By arranging the cover portion with such a recess and such a throughaperture, the nut can be captively attached to the cover portion andstill have a certain play in the direction of the nut rotation axis, inrelation to the cover portion.

According to another embodiment of the invention, the cover portion hasguiding means for guiding the first engagement means towards the secondengagement means. Thereby, it is facilitated to guide the cover portioncorrectly onto the first attachment means, since when the firstattachment means is inserted into the guiding means the first attachmentmeans is guided towards the second attachment means, whereby a correctarrangement of the cover portion to the body is achieved.

According to yet another embodiment of the invention, at least a part ofthe through aperture has substantially the same cross-sectionaldimension as a cross-sectional dimension of the first engagement means.Thereby, the inner walls of the through aperture functions as a guidingmeans for guiding the first engagement means towards the secondengagement means.

According to an alternative embodiment of the invention, the at leastone recess of the cover portion is arranged separately from the throughaperture. Thereby, the second distance B, the distance that the secondengagement means is movable relative the cover portion can be increasedand still it is possible to use the whole length of the through apertureas a guiding means for guiding the first engagement means towards thesecond engagement means.

According to a variant of this alternative embodiment, the secondengagement means comprises a holder portion and an engagement portion,the engagement portion being rotatably attached to the holder portion.Since the engagement portion is rotatably attached to the holderportion, the holder portion can be captively attached to the coverportion without having to be rotatable. Thereby, the cover portion doesnot have to allow rotational movement of the holder portion in the coverportion, resulting in less free space necessary for the secondengagement means in the cover portion.

According to another variant of the same alternative embodiment, atleast one attaching portion of the holder portion of the secondengagement means has a resilient structure. Thereby, the holder portioncan be snap-fitted into the at least one recess of the cover portion,which results in a quick captive mounting of the second engagement meansto the cover portion.

According to yet another variant of the same alternative embodiment, theat least one attaching portion comprises at least three attachingportions cooperating with at least three separate recesses of the coverportion. Thereby, a close fit can be achieved between the recesses andthe attaching portions of the nuts irrespective of tolerances inconstruction of cover portions and nuts.

According to another alternative embodiment of the invention, the atleast one recess for captively attaching the second engagement means tothe cover portion is a part of the through aperture for receiving thefirst engagement means. Thereby, the manufacture of the cover portion issimplified since recess and through aperture is in the same hole.

According to a variant of this alternative embodiment, the attachingportion of the second engagement means comprises a protrusion extendingin a direction away from the rotation axis of the second engagementmeans, and the cover portion comprises a protrusion extending in adirection towards the rotation axis of the second engagement means, saidprotrusions being arranged to cooperate such that the second engagementmeans is captively attached to the cover portion. Thereby, acost-efficient manner to captively attach the nut to the cover portionis achieved.

According to another variant of this alternative embodiment, the coverportion has a base portion and a plate portion, wherein the plateportion is attached to the base portion by means of an attachmentdevice, and wherein the protrusion of the cover portion is part of theplate portion. Thereby, captively mounting the nut to the cover portionis facilitated. Also, changing a defect nut is facilitated.

According to another embodiment of the invention, the arrangementcomprises at least two first engagement means and at least two secondengagement means, each of the at least two second engagement means beingarranged to cooperate with a respective one of the at least two firstengagement means. By using an arrangement according to the invention fora tool having at least two first engagement means with correspondingsecond engagement means, the user may engage a second engagement meansto its corresponding first engagement means fully, before another secondengagement means is engaged to its corresponding first engagement means.Thereby, assembling the cover portion to the body is facilitated.Similarly, when disassembling the cover portion from the body, a secondengagement means can be disengaged from its first engagement meansbefore the other second engagement means are even loosened from theircorresponding first engagement means, which facilitates thedisassembling of the cover portion from the body.

According to another aspect of the invention, a hand-held motor-driventool, such as a chain saw is claimed. The tool comprises a body and abar and an arrangement according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will in the following be described in more detail withreference to the enclosed drawings, wherein:

FIGS. 1 and 2 are cross sectional views of a part of a chain sawincluding a first embodiment of the present invention.

FIG. 3 is a perspective view of a nut according to the first embodimentof the present invention

FIG. 4 is a cross sectional view of a second embodiment of the presentinvention.

DESCRIPTION OF EMBODIMENTS

The present invention will be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. In thedrawings, like numbers refer to like elements.

Two preferred embodiments of attaching arrangements for hand-heldmotor-driven tools will be described with reference to FIGS. 1-4. Inthese embodiments, the hand-held motor-driven tool is a chain saw havinga body and a chain guiding bar that in a conventional manner supportsand guides a saw chain in a peripheral groove of the bar. The saw chainis driven by a sprocket wheel, hidden under a cover portion. The body isprovided with an engine that via a driving arrangement drives thesprocket wheel. The guide bar extends forwardly in the longitudinaldirection of the chain saw, and the rearward end of the bar is clampedbetween the body and the cover portion by means of a tighteningarrangement.

A first embodiment of the present invention is shown in FIGS. 1-3. FIGS.1 and 2 show a portion of a chain saw including the present invention. Acover portion 14 clamps a guide bar 1 to a body 2 by means of atightening arrangement, comprising two joints 10, 20. Each jointincludes a first 3 and a second 15 engagement means. The firstengagement means 3 is a bolt and the second engagement means 15 is anut.

Each bolt 3 has a first part 3 a and a second part 3 b. The first part 3a is securely attached to the body 2, e.g. by means of force fit, andthe second part 3 b extends from the body in a direction perpendicularto the guide bar plane and further through an aperture in the guide bar1 and through an aperture 14 c in the cover portion 14. The coverportion 14 has an inner surface 14 a, directed towards the body 2, andan outer surface 14 b, directed away from the body. A threaded part 3 cof the second bolt part 3 b, functioning as an engagement portion forengaging the nut to the bolt, projects at least partly beyond the outersurface 14 b of the cover portion. In order to clamp the bar 1 betweenthe cover portion 14 and the body 2, the nut 15 is engaged to thethreaded part 3 c of the bolt 3, and tightened.

The joint 20 in the right part of FIGS. 1 and 2 illustrates a conditionwhen the nut 15 and the bolt 3 are not engaged but the nut is captivelyconnected to the holder portion 14.

The joint 10 in the left part of FIGS. 1 and 2 illustrates a conditionwhen the nut 3 and the bolt 15 are engaged and the nut 15 is tightenedsuch that the joint clamps the bar 1 firmly between the body 2 and thecover portion 14.

In FIG. 2, reference A indicates a first distance, which is the lengthof thread engagement between the bolt 3 and the nut 15, i.e. thedistance in the direction of a nut rotation axis X that the nut 15 hasto move in thread engagement with the bolt 3 for firmly clamping the bar1 between the body 2 and the cover portion 14. When the nut is notengaged to the bolt, the nut can move a second distance B relative thecover portion 14, in the direction of the nut rotation axis X. In FIG.2, this second distance B is equal to the distance in the direction ofthe nut rotation axis X between the position of the nut 15 in the leftpart of the figure and the position of the nut 15 in the right part ofthe figure. The second distance B is equal to or greater than the firstdistance A, for allowing the nuts 15 to be loosened separately andindependently of each other when detaching the cover from the body.

The nut 15 comprises a hollow and internally threaded body portion 15 b,which is rotatably attached to a holder portion 15 a, as shown in FIG.3. The body portion 15 b is rotatable compared to the holder portion 15a around the nut rotation axis X.

The holder portion 15 a comprises a substantially circular portion thatbears against the body portion 15 b, and three attaching portions 15 c,formed as legs, extending from the periphery of the substantiallycircular portion. The legs 15 c are flat and directed away from the bodyportion 15 b in a direction substantially parallel to the nut rotationaxis X.

For each leg 15 c a slot extends from an end of each leg distal to thebody portion in a direction towards the body portion 15 b to a pointbetween the distal end of the leg 15 c and the substantially circularportion of the holder portion 15 a, such that the slot partly divideseach leg 15 c into two parallel parts. Each parallel part has aprotruding portion 15 d, shaped as a hook, in the distal end.

The cover portion 14 has oblong recesses 14 e for receiving the legs 15c of the nut holder portion 15 a. There is one separate recess 14 e foreach leg 15 c. The recesses 14 e are arranged separately from thethrough aperture 14 c of the cover portion, which aperture 14 c isarranged for receiving the bolt 3. The outer surface 14 b of the coverportion 14 has protruding portions 14 d arranged to co-operate with thehooks 15 d of the nut holder portion legs 15 c. The distance betweenthese protruding portions 14 d make the width of an opening of therecess 14 e smaller than the width of the nut holder portion leg 15 c atthe position of the hooks 15 d, such that the holder portion legs 15 care captivated within the recess 14 e. The depth of each recess 14 e isequal to or larger than the length of a holder portion leg 14 c. Therecesses 14 e may according to an alternative embodiment extend from theouter surface 14 a to the inner surface 14 b of the body, e.g. therecesses may be through apertures.

The slots of each leg 15 c make the structure of the nut holder portionlegs 15 c resilient. The outer ends of the two parallel parts can bepressed towards each other so that it is possible to snap the legs intothe openings of the recesses 14 e in the cover portion. Once insertedinto the recesses, the legs 15 c will revert to their original shape.The legs 15 c allow the nut 15 to move relative the cover portion 14 ina direction of the rotational axis X of the nut. When the hooks 15 d ofthe legs reaches the protruding portions 14 d of the cover portion 14,the protruding portions 14 d will co-operate with the hooks 15 d suchthat the movement of the nut 15 is stopped. In this way, the nut 15 iscaptively attached to the cover portion 14.

In FIGS. 1-3, the nut holder portion 15 a has three legs 15 c and thereare three recesses 14 e in the cover portion 14 for receiving the legs15 c. The number of legs 15 c and corresponding recesses 14 e may alsobe one, two, four or more.

The cross section in FIG. 1 is taken along a plane that intersects thecentres of the bolts 3. The cross section in FIG. 2 is taken along aplane that is parallel to the cross section plane in FIG. 1 and thatintersects a leg 15 c of the nut holder portion 15 a.

If an operator of a tool would like to e.g. change bars 1 using thearrangement described in FIGS. 1-3, the operator starts by loosening thenuts 15. Thanks to the second distance B being larger than the firstdistance A, the length of thread engagement, the nuts 15 can beunscrewed and loosened one at a time. When the nuts are loose, the cover14 including the nuts 15 captively arranged in the cover is removed fromthe chain saw. Thereafter, the operator removes the old bar 1 from thebody 2 and the bolts 3 of the tightening arrangement, and arranges a newbar 1 onto the bolts 3 such that the second part 3 b of the bolts passesthrough the apertures of the new bar 1.

When the new bar 1 has been arranged onto the bolts 3, the cover portion14 is arranged onto the bolts 3 by leading the bolts through the throughapertures 14 c of the cover portion. The through apertures 14 c of thecover portion also function as a guiding means for guiding the coverportion 14 onto the bolts 3 such that the cover portion 14 comes into acorrect position and such that the nuts 15 are arranged correctlytowards the end of the second parts 3 b of the bolts. In chain sawconfigurations having break components, such as a break band for akick-back guard (not shown), mounted in the cover portion it isimportant to obtain high precision in the position of the cover portion14. As the cover portion 14 is mounted onto the bolts 3 of body 2 thethrough aperture 14 c of the cover portion 14 gets guidance from thesecond part 3 b of the bolt 3. The diameters of the second part 3 b ofthe bolt 3 and the through aperture 14 c are preferably adapted toachieve a close fit and thereby a sufficient guidance in order to obtaina high precision in the position of the cover portion 4. According tothe present embodiment the precision in the position of the coverportion 14 is even further improved by the relatively long contact area,defined by the distance C in FIG. 1.

Thanks to the nuts 15 being captively attached to the cover portion 14in such a way that they are movable a second distance B relative thecover portion 14 in a direction of their rotation axis X, which seconddistance B is larger than the first distance A, the cover 14 can bearranged onto the bolts 3 such that the cover 14 can be pressed towardsthe bar 1 and the body 2 before the nuts 15 are tightened. This measurefacilitates a correct arrangement of the bar between the cover and thebody.

When the cover 14 has been arranged onto the bolts 3 and the bar 1 isclamped towards the body 2 by the cover 14, the nuts 15 are tightened bythreadingly engaging the nuts 15 to the bolts 3.

An alternative embodiment of the present invention is shown in FIG. 4wherein, as for the embodiment described with reference to FIGS. 1-3, acover portion 4 clamps a guide bar 1 to a body 2 by means of atightening arrangement, comprising two joints 10, 20. Each jointincludes a first 3 and a second 5 engagement means. The first engagementmeans 3 is a bolt and the second engagement means 5 is a nut.

The Joint 10 in the left part of FIG. 4 shows a state when the nut 5 isengaged to the bolt 3 so that the bar 1 is firmly clamped between thecover portion 4 and the body 2. The Joint 20 in the right part of FIG. 4illustrates a condition when the nut 5 and the bolt 3 are not engagedbut the nut is captively connected to the cover portion 4.

In this second embodiment, the bolts 3 may be similar to the boltsdescribed with reference to FIGS. 1-3. Each bolt has a first part 3 a,securely attached to the body 2, and a second part 3 b extending fromthe body through an aperture in the guide bar 1 and further through anaperture 4 c,4 g in the cover portion 4. The cover portion 4 has aninner surface 4 a, directed towards the body, and an outer surface 4 b,directed away from the body.

In contrast to the embodiment described with reference to FIGS. 1-3, aplate 4 f is attached to the outer surface 4 b of the cover portion bymeans of a screw 6. The second part 3 b of the bolt extends through anaperture in the plate 4 f. A threaded part 3 c of the second bolt part 3b projects beyond the plate 4 f, in a direction away from the coverportion 4. In order to clamp the bar 1 between the cover portion 4 andthe body 2, the nut 5 is engaged to the threaded part 3 c of the bolt 3,and tightened.

The nut 5 comprises an internally threaded body portion 5 c for engagingthe threaded part 3 c of the bolt. The internally threaded body portionis provided with a flange 5 d that is adapted to bear against the plate4 f when the nut 5 is tightened. To allow axial movement of the nut 5 ina direction of the nut rotation axis X, the nut also comprises anattaching portion 5 a, formed as a neck, adapted to be inserted into thethrough aperture 4 c, 4 g of the cover portion 4. The neck projects fromthe body portion in the direction of the nut rotation axis X from theflange 5 d and away from the body portion 5 c. The neck 5 a has aprotrusion, 5 b formed as a flange arranged at the end distal to theflange 5 d. The protrusion 5 b is adapted to co-operate with at leastone edge 4 d of the aperture of the plate 4 f, the at least one edgedefining a diameter of the aperture in the plate 4 f, so that the nutremains captively attached to the cover portion 4. A nut 5 arranged inthis way could rather easily be manufactured with low tolerances.

The aperture 4 c, 4 g in the cover portion has two parts; an inner part4 g closest to the inner surface 4 a of the cover portion 4, and anouter part 4 c closest to the outer surface 4 b of the cover portion 4.The diameter of the inner part 4 g is smaller than the diameter of theouter part 4 c. The outer part 4 c is arranged as a recess in theaperture 4 c, 4 g. More specifically, the diameter of the inner part 4 gis equal to or slightly larger than the diameter of the second part 3 bof the bolt and the diameter of the outer part 4 c is equal to or largerthan the diameter of the protrusion 5 b of the nut neck 5 a. The outerpart 4 c of the aperture 4 c, 4 g has a larger diameter than the innerpart 4 g for being able to receive the nut neck 5 a with its protrusion5 b.

The inner part 4 g, according to present embodiment, also functions as aguide for the cover portion 4. In chain saw configurations having breakcomponents, such as a break band for a kick-back guard (not shown),mounted in the cover portion it is important to obtain high precision inthe position of the cover portion 4. As the cover portion 4 is mountedonto the bolts 3 of body 2 the inner part 4 g of the aperture 4 c, 4 ggets guidance from the second part 3 b of the bolt 3. The diameters ofthe second part 3 b of the bolt 3 and the inner part 4 g of the aperture4 c, 4 g are preferably adapted to achieve a close fit and thereby asufficient guidance in order to obtain a high precision in the positionof the cover portion 4.

The diameter of the aperture in the plate 4 f is slightly smaller thanthe diameter of the outer part 4 c of the through aperture 4 c, 4 g ofthe cover portion 4, such that the edge 4 d of the plate 4 f aperturepartly covers the opening of the aperture 4 c, 4 g in the cover portion4.

When the nut 5 is loosened such that its threaded part is not engaged tothe threaded part 3 c of the bolt, as illustrated by joint 20 in FIG. 4,the nut 5 is still connected to the cover portion 4 because the diameterof protrusion 5 b is slightly larger than the diameter of the aperturein the plate 4 f.

In FIG. 4, reference A indicates a first distance, which is the lengthof thread engagement between the bolt 3 and the nut 5, i.e. the distancein the direction of the nut rotation axis X that the nut 15 has to movein thread engagement with the bolt 3 for firmly clamping the bar 1between the body 2 and the cover portion 14. When the nut is not engagedto the bolt, the nut is engaged to the cover portion 4 such that the nutcan move a second distance B relative the cover portion 4, in thedirection of the nut rotation axis X. In FIG. 4, this second distance Bis equal to the distance in the direction of the nut rotation axis Xbetween the position of the nut 5 of the joint 10 in the left part ofthe figure and the position of the nut 5 of the joint 20 in the rightpart of the figure. The second distance B is equal to or greater thanthe first distance A, for allowing the nuts 5 to be loosened separatelyand independently of each other. Reference C indicates the thickness ofthe cover portion 4, i.e. a distance between the outer surface 4 b andinner surface 4 a of the cover portion.

The walls of the inner part 4 g of the through aperture will function asa guiding means for guiding the bolt 3 towards the nut 5 when the coverportion 4 is lead on to the bolt 3 such that the bar 1 is clampedbetween the cover portion 4 and the body 2. Reference D indicates alength of the inner part 4 g of the through aperture 4 c, 4 g in thecover portion 4 in the direction of the nut rotation axis X functioningas a guiding means, i.e. a guiding length.

According to an embodiment, the aperture in the plate 4 f may be oblonghaving a smallest diameter similar to the diameter between the edges 4 dof the plate 4 f and a largest diameter larger than the diameter of thenut neck 5 a at the protrusions 5 b. Thereby, when the plate 4 f is notattached to the outer surface 4 b of the cover portion 4, it is possibleto insert the nut neck 5 a through the aperture in the plate 4 f wherethe aperture has a diameter similar to or broader than the diameter ofthe nut neck 5 a at the protrusions 5 b, by tilting the nut 5 relativethe plate 4 f, before inserting the nut neck through the aperture in theplate 4 f. When the plate is attached to the cover portion by means ofthe screw 6 such that the plate bears against the outer surface 4 b ofthe cover portion 4, and the nut neck 5 a extends into the aperture 4 c,4 g, the nut 5 can not be tilted and is thus captively attached to thecover portion.

In another embodiment, the aperture in the plate 4 f may be circularhaving a diameter similar to the distance between the edges 4 d of theplate. For making it possible to insert the nut neck 5 a in the apertureof the plate 4 f, the nut neck may have slots extending in the directionof the nut rotation axis X, the slots making the structure of the nutneck 5 a resilient. Thus it will be possible to compress the nut neck 5a and to snap it through the aperture in the plate 4 f. Once inserted,the nut neck 5 a will revert to its original shape, and the nut 5 iscaptively connected to the plate 4 f.

The plate 4 f can be a separate plate or a part of an already existingpart of the hand-held motor-driven tool, such as a spike or spike bumperof a chain saw.

Other embodiments of the present invention are also possible. Forexample, there could be only one bolt and one nut in the attachingarrangement.

Above, the tool is described as a chain saw. Although, the tool may beany kind of hand-held motor-driven tool in which a bar is clampedbetween a cover and a body, such as a hedge trimmer, clearing saw,trimmer, pole saw or a power cutter.

In the drawings and specification, there have been disclosed preferredembodiments and examples of the invention and, although specific termsare employed, they are used in a generic and descriptive sense only andnot for the purpose of limitation, the scope of the invention being setforth in the following claims.

1-19. (canceled)
 20. An arrangement for attaching a cover to a bar of asaw, the arrangement comprising: at least one first engagement device,having a first part and a second part, the second part having anengagement portion for engaging at least one second engagement device; acover portion adapted to bear against a bar; the at least one secondengagement device, captively attached to the cover portion, wherein thesecond engagement device is adapted to engage the engagement portion ofthe first engagement device for securing the cover portion to the bar,the second engagement device having a rotation axis; wherein the secondengagement device is arranged to move a first distance along theengagement portion of the first engagement device, in a direction of therotation axis of the second engagement device; when the first and secondengagement device are not engaged, the second engagement device iscaptively attached to the cover portion in such a way that it is movablea second distance relative the cover portion in a direction of therotation axis of the second engagement device, wherein the seconddistance is larger than the first distance, wherein the cover portionhas an inner surface that, when the cover portion is arranged to thebar, is directed towards the bar, and an outer surface that, when thecover portion is arranged to the bar, is directed away from the bar, thecover portion further having a through aperture extending between theinner and outer surfaces for receiving the second part of the firstengagement device, the cover portion further comprising at least onereceiving portion in which an attaching portion of the second engagementdevice is arranged for captively attaching the second engagement deviceto the cover portion and the at least one portion is arranged separatelyfrom the through aperture.
 21. The arrangement as recited in claim 20,wherein the first part of the at least one first engagement device issecurely arranged to a body.
 22. The arrangement as recited in claim 21,wherein the second part of the at least one first engagement deviceextends from the body.
 23. The arrangement as recited in claim 22, suchthat the bar is arranged between the cover portion and the body.
 24. Thearrangement as recited in claim 21, wherein the second engagement deviceis adapted to engage the engagement portion of the first engagementdevice for securing a bar between the cover portion and the body. 25.The arrangement according to claim 20, wherein the cover portion hasguiding device for guiding the first engagement device towards thesecond engagement device.
 26. The arrangement according to claim 20,wherein at least a part of the through aperture has substantially thesame cross-sectional dimension as a cross-sectional dimension of thefirst engagement device.
 27. The arrangement according to claim 20,wherein the second engagement device comprises a holder portion and anengagement portion, the engagement portion being rotatably attached tothe holder portion.
 28. The arrangement according to claim 27, whereinthe holder portion of the second engagement device has at least oneattaching portion extending away from the engagement portion the atleast one attaching portion extending into at least one receivingportion of the cover portion for captively attaching the secondengagement device to the cover portion.
 29. The arrangement according toclaim 20, wherein the attaching portion extends in a directionsubstantially parallel to the rotation axis.
 30. The arrangementaccording to claim 20, wherein the at least one attaching portion has atleast one protruding portion, the at least one protruding portion beingarranged to cooperate with at least one protruding portion of the coverportion for captively attaching the second engagement device to thecover portion.
 31. The arrangement according to claim 20, wherein the atleast one attaching portion of the second engagement device has aresilient structure.
 32. The arrangement according to claim 20, whereinthe at least one attaching portion comprises at least three attachingportions cooperating with at least three separate receiving portions ofthe cover portion.
 33. The arrangement according to claim 20, whereinthe attaching portion of the second engagement device comprises aprotrusion extending in a direction away from the rotation axis of thesecond engagement device, and the cover portion comprises a protrusionextending in a direction towards the rotation axis of the secondengagement device, said protrusions being arranged to cooperate suchthat the second engagement device is captively attached to the coverportion.
 34. The arrangement according to claim 20, wherein thearrangement comprises at least two first engagement device and at leasttwo second engagement device, each of the at least two second engagementdevice being arranged to cooperate with a respective one of the at leasttwo first engagement device.
 35. The arrangement according to claim 20,wherein the at least one first engagement device is a bolt and the atleast one second engagement device is a nut arranged to cooperate withthe bolt.